Powder detergent compositions comprising surfactants are known. Such compositions can be used, for example, as hard surface cleaners as well as laundry and automatic dishwasher cleaners. They can be used by placing an amount of powder into a volume of water and then using the resulting solution to clean the surface of interest. In the case of laundry cleaners, a measured amount of the powder is placed into a suitable washing machine. For automatic dishwashers, measured amount of powder is placed in the dishwasher, usually in dispensing cups. For difficult stains, a paste can be made with the powder and small amount of water and then rubbed on the surface. This is true for fabric as well as dish surfaces.
For some purposes it is desirable to have pre-measured doses can be prepared so that the user of the these compositions do not have to measure the appropriate amount of surfactant composition to use every time they wish to clean hard surfaces, as well as laundry and dish surfaces.
The present composition is especially suitable for use in a water-soluble container where the container is simply added to a large quantity of water and dissolves, releasing its contents. The favorable dissolution and dispersion properties of the composition of the present invention are particularly useful in this context.
Thus the present invention also provides a water-soluble container containing a composition as defined above. The water-soluble container is also suitable for laundry and automatic dishwasher compositions and use.
The water-soluble container may comprise a thermoformed or injection molded water-soluble polymer. It may also simply comprise a water-soluble film. Such containers are described, for example, in EP-A-524,721, GB-A-2,244,258, WO 92/17,381 and WO 00/55,068.
The method of thermoforming the container is similar to the process described in WO 92/17382. A first poly (vinyl alcohol) (“PVOH”) film is initially thermoformed to produce a non-planar sheet containing a pocket, such as a recess, which is able to retain the aqueous composition. The pocket is generally bounded by a flange, which is preferably substantially planar. The pocket may have internal barrier layers as described in, for example, WO 93/08095. The pocket is then filled with the aqueous composition, and a second PVOH film is placed on the flange and across the pocket. The second PVOH film may or may not be thermoformed. If the first film contains more than one pocket, the second film may be placed across all of the pockets for convenience. The pocket may be completely filled, or only partly filled, for example to leave an air space of from 2 to 20%, especially from 5 to 10%, of the volume of the container immediately after it is formed. Partial filling may reduce the risk of rupture of the container if it is subjected to shock and reduce the risk of leakage if the container is subjected to high temperatures.
The films are then sealed together, for example by heat sealing across the flange. Other methods of sealing the films together may be used, for example infra-red, radio frequency, ultrasonic, laser, solvent, vibration or spin welding. An adhesive such as an aqueous solution of PVOH may also be used. The seal desirably is also water-soluble.
For injection molding the containers of the present invention, the container or capsule generally comprises a receptacle part which holds the composition and a closure part, which may simply close the receptacle part or may itself have at least some receptacle function. The receptacle part preferably has side walls which terminate at their upper end in an outward flange in which the closure part is sealingly secured, especially if the closure part is in the form of a film. The securement may be by means of an adhesive but is preferably achieved by means of a seal, between the flange and the closure part. Heat sealing may be used or other methods such as infra-red, radio frequency, ultrasonic, laser, solvent, vibration or spin welding. An adhesive such as an aqueous solution of PVOH or a cellulose ether may also be used. The seal is desirably also water-soluble.
The closure part may itself be injection molded or blow molded. Preferably, however, it is a plastic film secured over the receptacle part. The film may, for example, comprise PVOH or a cellulose ether such as HPMC or another water-soluble polymer.
The container walls have thicknesses such that the containers are rigid. For example, the outside walls and any inside walls which have been injection molded independently generally have a thickness of greater than 100 μm, for example greater than 150 μm or greater than 200 μm, 300 μm or 500 μm. Preferably, the closure part is of a thinner material than the receptacle part. Thus, typically, the closure part is of thickness in the range 10 to 200 μm, preferably 50 to 100 μm, and the wall thickness of the receptacle part is in the range 300 to 1500 μm, preferably 500 to 1000 μm. The closure part may, however, also have a wall thickness of 300 to 1500 μm, such as 500 to 1000 μm.
Preferably, the closure part dissolves in water (at least to the extent of allowing the washing composition in the receptacle part to be dissolved by the water; and preferably completely) at 20° C. in less than 3 minutes, preferably in less than 1 minute.
The receptacle part and the closure part could be of the same thickness but in this event the closure part may, for example, be of higher solubility than the receptacle part, in order to dissolve more quickly.
In the manufacturing method, the array, formed by injection molding, is fed to a filling zone, and all the receptacle parts are charged with the washing composition. A sheet of a water-soluble polymer such as PVOH or a cellulose ether may then be secured over the top of the array, to form the closure parts for all the receptacle parts of the array. The array may then be split up into the individual washing capsules, prior to packaging, or it may be left as an array, for packaging, to be split by the user. Preferably, it is left as an array, for the user to break or tear off the individual washing capsules. Preferably, the array has a line of symmetry extending between capsules, and the two halves of the array are folded together, about that line of symmetry, so that closure parts are in face-to-face contact. This helps to protect the closure parts from any damage, between factory and user. It will be appreciated that the closure parts are more prone to damage than the receptacle parts. Alternatively two identical arrays of washing capsules may be placed together with their closure parts in face-to-face contact, for packaging.
In all cases, the polymer is formed into a container or receptacle such as a pouch which can receive the composition, which is filled with the composition and then sealed, for example by heat sealing along the top of the container in vertical form-fill-processes or by laying a further sheet of water-soluble polymer or molded polymer on top of the container and sealing it to the body of the container, for example by heat sealing. Other methods of sealing the films together may be used, for example infra-red, radio frequency, ultrasonic, laser, solvent, vibration or spin welding. An adhesive such as an aqueous solution of PVOH may also be used. The seal desirably is also water-soluble.
Desirably the water-soluble polymer is PVOH. The PVOH may be partially or fully alcoholized or hydrolyzed. For example, it may be from 40 to 100% preferably 70 to 92%, more preferably about 88%, alcoholized or hydrolyzed, polyvinyl acetate. When the polymer is in film form, the film may be cast, blown or extruded.
The water-soluble polymer is generally cold water (20° C.) soluble, but depending on its chemical nature, for example the degree of hydrolysis of the PVOH, may be insoluble in cold water at 20° C., and only become soluble in warm water or hot water having a temperature of, for example, 30° C., 40° C., 50° C. or even 60° C. It is preferable that the water soluble polymer is soluble in cold water.
Another useful and preferred material which can be used to encapsulate the powder compositions of the present invention is a nonwoven polyvinyl alcohol fabric available from BBA Nonwovens of South Carolina. Sachets made from this material are optimally used in warm (e.g., 40° C.) water.
The water soluble containers of the present invention find particular use where a unit-dosage form of the composition is required which is then diluted prior to use. Thus, for example, the composition may be useful as a hard surface cleaner (for example, floors, bathroom surfaces, windows) which is diluted prior to use. The water soluble container to be used for hard surface cleaners can take any shape, such as an envelope, sachet, sphere, cylinder, cube or cuboid (i.e. a rectangular parallelepiped whose faces are not all equal) where the base is square, circular, triangular, or oval, but water soluble containers of rounded cuboid or cylindrical shape are preferred; rounded cuboid for use in, for example, a bucket of water and cylindrical when used as a refill for a trigger bottle. For the rounded cuboid water soluble container, the water soluble container can have dimensions such as, for example, having a length of 1 to 5 cm, especially 3.5 to 4.5 cm, a width of 1.5 to 3.5 cm, especially 2 to 3 cm, and a height of 1 to 2 cm, especially 1.25 to 1.75 cm. The water soluble container may hold, for example, from 10 to 40 grams of the composition, especially from 15 to 25 grams of the composition of the present composition. For the cylindrical shape, the water soluble container diameter should be such that the water soluble container fits through the opening of a trigger bottle, generally about 2 cm. The length of the water soluble container can be about 1 to 8 cm. Such water soluble containers hold about 3 to about 25 grams of composition. However, it should be understood that there is no theoretical limitation, in either size or shape, and what is suitable will normally be decided upon the basis of the “dose” of the water soluble container's contents, the size of any aperture the water soluble container may have to pass through, and the available means of delivery.
In some embodiments, a single layer film for both the top and bottom the packet can be used or a laminate film of two or more layers of PVOH or other water soluble film can be used on either the top or bottom or on both top and bottom of the packet. For the cylindrical container, the film can also be single layer or a laminate of two or more layers of PVOH or other water soluble film.